1. Field of the Invention
The present invention relates to an inkjet recording apparatus and a thermal insulation method, more particularly to thermal insulation technology for stabilizing the ambient temperature around an inkjet head.
2. Description of the Related Art
An inkjet recording apparatus for forming a desired image on a recording medium by using an inkjet method is known as a general-purpose image recording apparatus. It is necessary for achieving good performance of the inkjet recording apparatus to create an environment where an inkjet head is allowed to stably eject and deposit ink droplets onto a recording medium, and also to shortly dry the ink droplets deposited on the recording medium. For example, it is important to keep the temperature around the inkjet head constant in order to realize the environment where the stable ink droplet ejection operation is performed. On the other hand, in order to dry the ink in a short time, it is effective to perform a heating process immediately after the ink droplet deposition operation.
In order to speed up the process of drying the ink on the recording medium after the ink droplet deposition operation, it is preferred to bring the inkjet head close to a drying process unit, so that the drying process can be started immediately after the deposition of the ink droplets. In this case, the inkjet head that needs to keep its temperature (e.g., 30° C.) lower than the drying process temperature, which is approximately 60° C. to 80° C., is brought close the drying process unit that needs to keep its temperature high as mentioned above, in order to improve its drying performance.
On the other hand, it is desirable that the inkjet head and the drying process unit are kept away from each other as far as possible in order to maintain the relatively low temperature of the inkjet head and the relatively high temperature of the drying process unit; however, this makes it difficult to realize the efficient drying process described above.
In other words, various kinds of efforts need to be made in order to simultaneously realize the conflicting environments, i.e., the relatively low temperature around the inkjet head and the relatively high temperature of the drying process unit. The configuration of an inkjet recording apparatus in the related art has a cooling device that performs a cooling process on the inkjet head, wherein the cooling device forcibly cools the inkjet head.
However, when the inkjet recording apparatus is provided with the cooling device for cooling the inkjet head and the periphery thereof, because the ambient temperature of the inkjet head is raised by the heat generated by the drying process unit due to the close arrangement between the inkjet head and the drying process unit, the size of the entire apparatus increases, as well as the consumption power in the entire apparatus. Moreover, when the ambient temperature of the inkjet head exceeds a predetermined temperature, it causes troubles such as condensation on a nozzle surface of the inkjet head and a sensor failure to detect floating of a sheet of recording medium. Therefore, additional parts are required for coping with such troubles; which requires a space large enough to arrange these additional parts in the entire apparatus, leading to an increase in the costs.
Although it is considered to arrange a member having thermal insulating properties at a position between the inkjet head and the drying process unit to insulate the inkjet head from the heat generated by the drying process unit, this requires the space for disposing the thermal insulation member, and disposing the thermal insulation member on a path for conveying a recording medium not only requires the space but also creates various barriers.
Japanese Patent Application Publication No. 2006-069739 discloses a recording apparatus in which an air curtain is disposed between a print unit and a paper feed unit located in an upstream side of the print unit, and a space of the upstream side of the print unit is thereby separated from a space of the print unit. However, this recording apparatus is provided with the air curtain to prevent the entry of foreign matter into the periphery of the print unit, but has no configuration for insulating the print unit from heat generated by other process units. Furthermore, Japanese Patent Application Publication No. 2006-069739 does not focus on the impacts of the heat on the print unit, the heat being generated as a result of the drying process, and is silent about technology for solving the problems associated with the impacts of the heat.